300 RUM is managable w/out a brake whereas the 338 RUM IMO is not really so. However you must take into account I weigh 140#
I shot a 300 RUM barrel out in 2 years, no brake on it. I shot it well enough that I didn't wanna spend the money to put one on there. When it shot out, I rebarreled to 338 EDGE and definately needed the brake w/300g bullets in mind. I shot a friends 338 RUM in an XCR however with max loaded 250g ABs and it wasn't a pleasant experience to me anyways, a lot more rock then my 300 RUM LSS ever had with 200-220s. I dont think I could shoot a 338 RUM or EDGE very well at LR without a brake for very long is what I'm getting at. Remember though, I weigh 140# is all, but I think I have somewhat of a high tolerance for recoil, definately more then most, especially if you take my size into consideration if you base most peoples limit at 20-25lbs which is roughly an 06, a 300 RUM with 220s is my limit with no brake, which if you ask me, is pretty good considering my weight, and the fact the rifle has about 45 lbs of recoil.
Recoil is not your friend when shooting LR, get a muzzle brake and get rid of it...
NF is a great way to go, but remember they are 2 pounds worth of scope. To heavy IMO for a hunting rifle scope. Leupolds are much much lighter. I can put spikes on an elk on 20x at 1000 yards at shooting light so I dont care how good NF are, my VX3 does what I need it to do at a lot less cost and weight is all.
My 338 EDGE weighs about 12.5 all scoped up ready to shoot, maybe 13 lbs. With 300g SMK's at 2825fps and even with the somewhat heavy rifle and the brake, the recoil is still a lot more then I like for a day of LR shooting. Its still a beast, and its not so much more of the big "push" you get with bigger rifles, it still has that "sharp smack" in your face when you touch that 1.5# trigger off everytime. Its kinda a mind game with this rifle, you just gotta know its gonna let you know when you pull the trigger everytime so be prepared...My dad scoped himself so bad the first time he shot it, he never wanted to shoot it again, thats how I ended up with it, LOL. Its a no joke powerhouse. First time I hit the 15" gong at 1K, it ripped the gong right off the stand...Had to improvise on how I hung the gong after that.